To convey a similar sentiment, you might use phrases like:
* In Scottish Gaelic: Something like "Dia leat" (God with you) or "Slàinte mhath air do thuras" (Good health on your journey) would be appropriate, depending on the context. You could also use a more general blessing like "Beannachd leat" (Blessing with you).
* In Scots: You might say something like "Guid speed tae ye" (Good speed to you), which is a direct borrowing of the English, but sounds more natural to a Scots speaker. Other options include "May ye hae a guid journey" or "Safe travels."
The best choice depends on the specific situation and the level of formality desired. "Guid speed tae ye" is a good general option that most Scots speakers will understand and appreciate.